Why did he lie about where he was? Please help?

I met a guy recently that goes to the same uni as me, and we've been on a few dates since. We hit it off straight away; we're both very intellectual and are doing similar courses. We're able to have educated discussions with each other that we've made clear we haven't been able to have with other people, and we've got so much in common that we both find it pretty astounding.

We had exams and I texted him saying I hope his last exam went well. He didn't reply that night, instead he replied the next morning, also apologizing for the late reply 'as he was at a business function last night'. This was a few weeks ago, but I found out the other day after scrolling down Facebook that that night he was at a massive clubbing party (he went with guy friends only but met new girls there obviously) instead of supposedly 'being at a business function'.

When I had texted him that night, everything in the first paragraph applied except for us having lots in common, as we had talked a lot but not actually gone on our first date yet, so all the intellect and the attraction was there we just didn't know YET that we had loads in common. Anyways my question is, why do you think he lied about where he was? Or even, why say he was at a business function instead of admitting he went to a clubbing party?